Originally Posted by rdivaldi
IMO it's a little bit of both. I think in any sport you get into habits with your motions, whether it be a baseball swing, a tennis serve, or throwing a football. You can always learn how to do something differently, but unless you concentrate on it, you can easily slip back into your old way of doing things.
Just to expand on what you said...... basically, players develop muscle memory over the years. In a nutshell, a swing has to be crafted so that once a hitter decides to swing, then he does so immediately without any thought. A hitter has about three-tenths of one second to decide whether to swing, where to swing and at what speed the ball is coming at him. The swing itself once started is finished by simple muscle memory. Its similar to many things we do daily that we never thing about, just because we have trained our body to do them. They become 2nd nature.
To change that is easier for some than others. That is where the mental aspect comes in. That doesn't mean someone that can't change as easily as another is dumb. People are "wired" differently. I used to teach hitting lessons to kids and some kids can pick up on changes you make or on trying to do something new almost immediately. Others struggle and seem stiff while trying to change what they have always done. It is less exaggerated but similar at a professional level.
Once you try to make a change, until it becomes second nature, you are thinking about it. The one thing that is true in the batters box is there is no time to think about the mechanics of your swing. If that is in the back of your mind at all, then it will slow down the process, often making the swing longer or awkward, especially on breaking balls.